Pigs, horses, cows, chickens, cocks, ducks (optional), donkeys (optional), sheep, goats, cats (optional), dogs (optional), bull, bunny (optional), turkey (optional).
no bond is not an optional money. A cheque can be a form of optional money.
no, it is optional
The word problem was optional.
The opposite of compulsory (compelled) would be voluntary or optional.
optional recovery number
what is optional recovery number
it is entirely optional
The optional sacraments are Marriage, Ordination, and Unction.
The math question was optional, but every one did it.
The "mixing center" is optional
The antonym of compulsory is optional or voluntary.